The present invention relates to a beer contained in a container which has been substantially fermented as a product beer and contains yeast.
More specifically, the present invention relates to a beer contained in a container which is prevented from changing its flavor after it has been charged into the container.
Fresh beer which has been just produced in a brewery has a good taste, but it is inevitable that a change in the flavor of the beer will occur with the passage of time even if it is a draft beer or one which has been subjected to heat treatment.
The change of the flavor of a beer is believed to be caused partly by oxidation. It is evident that beer is oxidized to a certain degree when consumers drink the beer which has been charged into containers for consumers, and thus the problem of the change of the flavor as mentioned above will be caused. If the oxidation of beer is suppressed to an extremely low level, the flavor will not be changed to an extent causing problems, but when the beer has been oxidized seriously, it will generate an unpleasant smell, the socalled oxidized flavor.
For the purpose of preventing the oxidation of beer after it has been charged into a container, beer manufacturers are making efforts for reducing the air content in the beer containers or for reducing the periods of storage in the market place.
In addition to such a passive prevention of oxidation or protection from oxidation, there is a method of adding ascorbic acid as an anti-oxidizing agent, and in fact the addition of ascorbic acid to beer is authorized officially by the Liquor Tax Act in Japan.
On the other side, a beer product containing yeast is being produced in Europe and other places. This known beer is produced by adding yeast to a beer the fermentation of which has not been substantially completed as a product beer and performing its final fermentation, that is, the secondary fermentation, in bottles to brew a beer having a characteristic flavor, which further comprises the effects of the use of wheat malt, the action of lactobacillus or the like.